KR20210137709A - Pressure feedback servo-valve - Google Patents

Abstract

The present invention relates to a pressure feedback servo-valve comprising: a torque motor configured to operate a flapper that selectively opens and closes a pressure nozzle according to an external signal; a body unit having one side connected to the torque motor, and including a sleeve communicating with an A port, a B port, a tank port, and a pressure port; a spool capable of being reciprocating in a predetermined section within the sleeve, and for determining the flow path of a fluid according to a position; and a pair of pressure feedback channels capable of transmitting pressure from the A port and the B port to both ends of the spool. The pressure feedback servo-valve allows the pressure feedback channels connected to a rod side to transmit feedback force to the spool, thereby directly controlling force and torque by using only an electrical signal without a separate sensor. In addition, the pressure feedback servo-valve can be backdrivable and enables safe control interacting with an external environment. Moreover, the pressure feedback servo-valve can alleviate the frictional force of the spool and the interference caused by concentricity to ease the hysteresis problem of the existing servo-valve, thereby performing more accurate control.

Description

PRESSURE FEEDBACK SERVO-VALVE

The present invention relates to a pressure feedback servo valve, and more particularly, to a servo valve capable of force/torque control by feedback on a change in pressure generated from a load connected to the outside.

A servo valve refers to a valve that can control flow or pressure by continuously moving a spool of a valve according to an electrical signal applied to the valve. These servo valves are used in various hydraulic systems, and are applied in various fields such as aircraft, automobiles, ships, and robots that require strong force.

Korean Patent Registration No. 1110280 is disclosed in relation to a conventional servo valve. However, the conventional servo valve has a characteristic that the hydraulic control system is easy to control speed and position, but is disadvantageous in controlling force and torque, and cannot actively cope with external force applied to the driving unit from the outside. Therefore, the hydraulic system provided in equipment that needs to interact with the external environment, such as a robot, requires additional equipment such as a force/torque sensor. there was.

In addition, the servo valve had a problem of 'hysteresis' in which the position of the spool could not be precisely controlled by the input signal due to friction between the spool and the valve body, making it difficult to accurately control force/torque.

Republic of Korea Patent No. 1110280

An object of the present invention is to provide a servovalve having improved control performance by driving a servovalve through pressure feedback and improving hysteresis to solve the problems of the prior art.

As a means of solving the above problem, a torque motor configured to operate a flapper that selectively opens and closes a pressure nozzle according to an external signal, one side is connected to the torque motor, and A port, B port, tank port and pressure port A body portion comprising a communicating sleeve, a spool configured to be reciprocable in a predetermined section within the sleeve, and a spool configured to determine a flow path of a fluid according to a position, and pressure is applied to both ends of the spool from port A and port B, respectively A hydraulic feedback servovalve may be provided that includes a pair of pressure feedback channels configured to be transferable.

On the other hand, the spool may be configured to move in the longitudinal direction according to the pressure difference acting on both ends when the pressure is changed in port A or port B.

In addition, the spool may further include a pair of pressure feedback ports extending in the longitudinal direction so that both ends can be respectively inserted into the pair of pressure feedback channels.

On the other hand, the cross-sectional area of the pressure feedback port may be configured to be smaller than the inner diameter of the sleeve.

In addition, the pair of pressure feedback ports may be configured to remain respectively inserted into the pair of pressure feedback channels within a longitudinal stroke of the spool.

Further, the pressure feedback port may include at least one groove cut along a turning radius to reduce frictional force when moving in the longitudinal direction within the pressure feedback channel.

Meanwhile, the pressure feedback channel may be formed in the body portion.

In addition, the body portion, the torque motor is connected to the upper side, is configured so that the sleeve and the spool can be arranged on the inside, the A port, the B port, the tank port and a hydraulic manifold in which a plurality of flow paths for connecting to the pressure port are formed. , A pair of hydraulic housing blocks configured so that both ends of the spool exposed on both sides of the hydraulic manifold can be respectively inserted, and a jig configured to relatively move the pair of hydraulic housing blocks with the hydraulic manifold can do.

On the other hand, the jig is fixed to the hydraulic manifold at a plurality of points, is provided with a hydraulic housing block accommodating groove configured to accommodate the hydraulic housing block inside, and is formed by penetrating into the hydraulic housing block accommodating groove at a plurality of points. An adjustment screw insertion hole may be formed.

On the other hand, the adjustment screw insertion hole is formed in two directions perpendicular to the longitudinal direction of the spool, and may be configured to move the position of the hydraulic housing block as the adjustment screw is inserted.

On the other hand, one end is connected to the flapper, the other end is supported on the central portion in the longitudinal direction of the spool, the spool may further include a feedback spring that provides a restoring force to return to the neutral position.

Meanwhile, at least a portion of the hydraulic feedback channel may be formed in the hydraulic housing block, and the pressure feedback port of the spool may be configured such that at least a portion is inserted into the hydraulic feedback channel formed in the hydraulic housing block.

The pressure feedback servo valve according to the present invention can control the change in pressure acting on the rod side by feedback, so that the force/torque can be actively controlled. use the structure. In addition, through precise control to match the concentricity of the shaft between the spool and the pressure feedback port, it is possible to improve the hysteresis problem and improve the control performance of the servo valve.

1 is a perspective view of a pressure feedback servo valve according to an embodiment of the present invention.
2 is an exploded perspective view of a pressure feedback servo valve according to an embodiment of the present invention.
3 is a cross-sectional view taken along the central axis of the spool in FIG. 2 .
4 is a partial cutaway view showing one side of the hydraulic manifold and the spool.
FIG. 5 is a partially enlarged view illustrating the pressure feedback port of FIG. 3 .
6 and 7 are operational state diagrams of the pressure feedback servo valve according to the present invention.
8 is a perspective view showing a jig and a hydraulic manifold of another embodiment according to the present invention.
9 is a state diagram of a jig for aligning the axis between the spool and the manifolds at both ends.

Hereinafter, a pressure feedback servo valve according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. And in the description of the embodiments below, the name of each component may be called another name in the art. However, if they have functional similarity and identity, even if a modified embodiment is employed, it can be regarded as an equivalent configuration. In addition, the code added to each component is described for convenience of description. However, the contents shown in the drawings in which these symbols are indicated do not limit each component to the scope within the drawings. Similarly, even if an embodiment in which the configuration in the drawings is partially modified is employed, if there is functional similarity and sameness, it can be regarded as an equivalent configuration. In addition, in view of the level of a general engineer in the art, if it is recognized as a component to be included of course, a description thereof will be omitted.

1 is a perspective view of a pressure feedback servo valve according to an embodiment according to the present invention, FIG. 2 is an exploded perspective view of a pressure feedback servo valve according to an embodiment according to the present invention, and FIG. 3 is the central axis of the spool 250 in FIG. It is a cross-sectional view cut out as a reference.

Referring to FIG. 1 , the pressure feedback servo valve according to the present invention may include a torque motor 100 and a body part 200 .

The torque motor 100 is configured to selectively open and close the nozzle 270 of the body 200 to be described later by changing the position of the flapper 120 provided therein. The torque motor 100 is connected to one side of the body part 200 , and a connection part with the body part 200 may be sealed so that an internal hydraulic pressure is not connected to the outside.

The torque motor 100 may include a feedback spring 130 provided in the flapper 120 . The feedback spring 130 may be configured to provide a restoring force capable of returning to the original position when the spool 250 is moved to one side. One side of the feedback spring 130 may be connected to the central axis of the flapper 120 or the armature 110 , and the other side may be installed to be supported by the central portion of the spool 250 in the longitudinal direction. The feedback spring 130 provides a force for the spool 250 to increase its restoring force, thereby overcoming the resistance caused by the frictional force with the sleeve 260 when the spool 250 moves and returning it to a neutral position, that is, the central position. hysteresis can be overcome. Therefore, however, the torque motor 100 may be configured to include the armature 110, the flapper 120, a permanent magnet, and an electromagnet, and since the configuration of the torque motor 100 is a widely used configuration, further detailed description should be omitted.

The body part 200 may be configured to selectively switch a path through which the fluid flows according to the driving of the torque motor 100 . The body 200 may include a hydraulic manifold 210 , a hydraulic housing block 220 , and a jig 230 .

The hydraulic manifold 210 is configured to include a plurality of flow paths formed on the inside, and the spool 250 may be positioned so that the spool 250 can move linearly in one direction on the inside. The hydraulic manifold 210 may include a central manifold 211 , a lower manifold 212 , and a side manifold 213 .

The central manifold 211 is configured such that the flapper 120 acts by the operation of the torque motor 100 so that the flow path of the flow path can be switched. The central manifold 211 may include a nozzle 270 , a sleeve 260 , and a spool 250 .

The nozzles 270 are provided to face each other in parallel, and when the angle of the flapper 120 is changed, the injection port may be closed. When the nozzle 270 is closed by the flapper 120 , a pressure is increased inside the nozzle 270 in which the injection port is closed, and the increased pressure is transmitted to the spool 250 to move the spool 250 .

The sleeve 260 is configured such that the spool 250 can be accommodated on the inside, and can be configured with a step difference that can be smoothly linearly moved to each other. The sleeve 260 may be laterally inserted into the central manifold 211 . The sleeve 260 may be configured in a cylindrical shape, and may include a plurality of ports provided in the central manifold 211 and a plurality of openings formed in a radial direction so that the inside and outside of the sleeve 260 may be in fluid communication. have.

The spool 250 is configured to move linearly inside the sleeve 260 to divert fluid movement. The spool 250 is configured to be linearly moved in the extended longitudinal direction. The spool 250 is configured in a cylindrical shape as a whole, and may include an extension 251 formed by extending radially at a plurality of points of the cylinder. The space between the expanded part 251 and the expanded part 251 becomes the spool chamber 254 , and when hydraulic pressure is received, it may be configured so that a force by pressure can be applied to the longitudinal direction of the spool 250 . The channel in fluid communication with the spool chamber 254 may be switched depending on the position of the spool 250 , and the channels in fluid communication with the spool chamber 254 transmit pressure to each other, and fluid through the spool chamber 254 . can be moved.

Meanwhile, a pressure feedback port 252 may be provided at both ends of the spool 250 to feed back a pressure change applied by an external load. The pressure feedback port 252 may be formed to extend at both ends in the longitudinal direction of the spool 250 . The pressure feedback port 252 may be configured to transmit an external load, for example, a pressure acting on the A port 310 and the B port 320 connected to the chamber of the actuator. Therefore, when the pressure acting on the A port 310 and the B port 320 is changed, the force acting in the longitudinal direction of the spool 250 also changes, so that the position of the spool 250 is moved. As a result, the spool 250 can receive pressure feedback from an external actuator even without a separate operation of the torque motor 100 .

A pair of pressure feedback ports 252 may be respectively inserted into a pressure feedback channel 350 formed in a side manifold 213 to be described later. The pressure feedback port 252 is configured to be sealed while being inserted into the pressure feedback channel 350 , and may be configured to be movable by a predetermined length in the longitudinal direction. That is, the pressure feedback ports 252 on both sides within the longitudinal stroke of the spool 250 are to be maintained inserted into the pressure feedback channels 350 provided in the pair of side manifolds 213 . can Therefore, the pressure feedback port 252 can continuously receive a feedback of the pressure caused by the external pressure change regardless of the horizontal position of the spool 250 .

The lower manifold 212 may be provided with a plurality of channels connected to an external load, for example, an actuator. The lower manifold 212 may be provided on the lower side of the central manifold 211 , and the A port 310 and B port 320 configured to be in fluid communication with the sleeve 260 of the central manifold 211 . ) may be provided.

The side manifold 213 may be configured to connect the central manifold 211 and the lower manifold 212 in the lateral direction, that is, at both ends in the x-axis direction in FIG. 2 . The side manifold 213 may include a hole through which the pressure feedback port 252 of the spool 250 is penetrated in the lateral direction so that it can be inserted into the hydraulic housing block 220 to be described later.

The hydraulic housing block 220 is configured so that pressure can be fed back to the pressure feedback ports 252 provided on both sides of the spool 250 . The hydraulic housing block 220 is provided on the outer sides of both sides of the side manifold 213 , and may be configured to be supported on both sides of the spool 250 . The hydraulic housing block 220 includes a pressure feedback port accommodating groove 221 that is formed to penetrate in the longitudinal direction of the spool 250, that is, in the x direction so that the pressure feedback port 252 of the spool 250 can be inserted. can be configured. The pressure feedback port receiving groove 221 functions as a part of the pressure feedback channel 350, and may be configured to have an inner diameter that is slidable in the x direction in a state in which the pressure feedback port 252 of the spool 250 is inserted. . The pressure feedback port accommodating groove 221 may have a pressure feedback port 252 inserted from one side thereof, and may be in fluid communication with the pressure feedback channel 350 from the other side.

The jig 230 may be provided outside the side manifold 213 and the hydraulic housing block 220 . A hydraulic housing block accommodating groove ( 231) may be provided. A pressure feedback channel 350 may be provided inside the jig 230, and the pressure feedback channel 350 may be formed to extend from one outer surface of the jig 230 to the hydraulic housing block receiving groove 231, Finally, it may be formed in fluid communication with the pressure feedback port receiving groove 221 of the hydraulic housing block 220 .

4 is a partial cutaway view showing one side of the hydraulic manifold and the spool, and FIG. 5 is a partially enlarged view showing the pressure feedback port 252 of FIG. 3 .

Referring to FIG. 3 , the pressure feedback ports 252 extending in the longitudinal direction of the spool 250 at both ends of the spool 250 are inserted into the pressure feedback port receiving grooves 221 of the hydraulic housing block 220 . The state in which there is is shown. The pressure feedback port 252 allows the spool 250 to continuously receive pressure from the pressure feedback channel 350 at both ends even if the position in the longitudinal direction is changed. Although not shown, the pair of pressure feedback channels 350 are configured to be in fluid communication with the A port 310 and the B port 320 from the outside, and directly apply pressure from the actuator connected to the outside ( 252) can be modified and applied to various configurations that can be applied to it.

Referring to FIG. 4 , in the hydraulic manifold 210 , fluid movement paths of various paths may be formed. Specifically, the pressure port 340, the A port 310, and the B port 320 are formed by penetrating in the vertical direction from the lower manifold 212, and configured to be in fluid communication with the spool 250 side of the central manifold. can be

The lower manifold 212 and the side manifold 213 may be formed with at least a portion of the hydraulic feedback channel 350 for transferring hydraulic pressure from the A port 310 to the pressure feedback port 252 of the spool 250 . have.

Specifically, the lower manifold 212 has a 1-1 hydraulic feedback channel 351 extending in the horizontal direction from the B port 320 , and a 1-2 hydraulic pressure formed in the side manifold 213 . It may be coupled to a feedback channel 352 . The 1-2 hydraulic feedback channel 352 is formed in the horizontal and vertical directions inside the side manifold 213 and may be in fluid communication with the hydraulic feedback port receiving groove 221 of the hydraulic housing block 220 on one side. .

Also, in the lower manifold 212 , a 2-1 hydraulic feedback channel 353 is formed extending from the A port 310 in the horizontal direction, and a 1-2 hydraulic feedback channel is formed in the side manifold 213 . (354) can be connected. The 2-2 hydraulic feedback channel 354 is formed in the horizontal and vertical directions inside the side manifold 213 and may be in fluid communication with the hydraulic feedback port receiving groove 221 of the other hydraulic housing block 220 . .

As a result, the hydraulic feedback panel 350 is formed in the hydraulic manifold 210 to transmit pressure from the A port 310 and the B port 320 to the pressure feedback port 252, which is both ends of the spool 250, so that an external force The position of the spool 250 can be changed by feeding back the change in pressure generated at the A port 310 and the B port 320 side by the .

Referring to FIG. 5 , the pressure feedback port 252 has a cylindrical shape and is provided on the end side of the spool 250 , and has at least one groove along the circumferential direction with respect to the central axis in the longitudinal direction of the spool 250 on the outside. (253) may be formed. The groove 253 of the pressure feedback port 252 is configured to minimize the frictional force between the pressure feedback port receiving groove 221 and the outer surface of the pressure feedback port 252, and thus smooth the horizontal movement of the spool 250. can be secured.

Hereinafter, the operating principle of the pressure feedback servo valve according to the present invention will be described with reference to FIGS. 6 and 7 . 6 and 7 are operational state diagrams of the pressure feedback servo valve according to the present invention. In this drawing, components are simplified for convenience of description.

Referring to FIG. 6 , a flow path capable of fluid communication with the spool 250 , that is, a port A 310 , a port B 320 , a tank port 330 and a pressure port 340 are configured. The pressure port 340 also supplies hydraulic pressure to the pair of nozzles 270 . The A port 310 and the B port 320 may be connected to an external load, that is, an actuator.

One side of the A port 310 is in fluid communication with the pressure feedback channel 350 , and the pressure acting on the A port 310 acts on the pressure feedback port on the left side of the spool 250 in FIG. 6 . Similarly, one side of the B port 320 is in fluid communication with the pressure feedback channel 350 , and the pressure acting on the B port 320 acts on the pressure feedback port 252 on the right side in FIG. 5 .

Referring to FIG. 7 , a state in which the torque motor 100 is operated by the user's input and the spool 250 is moved to the left in FIG. 7 is shown. The spool 250 moves to the left so that the A port 310 and the pressure port 340 are in fluid communication to supply pressure. In addition, the B port 320 is in fluid communication with the tank port 330 to recover the fluid. At this time, the supply pressure Ps is applied to the hydraulic feedback port on the left, and the recovery pressure Pr, which is smaller than the supply pressure Ps, is applied to the hydraulic feedback port on the right.

The spool 250 receives a restoring force F according to the difference between the supply pressure Ps and the recovery pressure Pr. Here, the cross-sectional area of the pressure feedback port 252 is configured to be smaller than the expanded portion 251 of the spool 250 so that the magnitude of the restoring force by the hydraulic pressure that is fed back becomes smaller than the driving force for driving the spool 250 . Therefore, the restoring force itself by the hydraulic feedback is set not to be greater than the driving force, so that the influence on the direct driving of the spool 250 can be determined within a certain ratio.

When the fluid of the supply pressure is supplied to the chamber 1300 formed between the rotator vane 1210 and the fixed part vane 1110 of the actuator 1000 by the operation of the spool 250, the rotator 1200 of the actuator is rotated counterclockwise in FIG. 6 . At this time, when an external force resisting the driving direction is applied from the outside of the rotary actuator, the pressure of the inner chamber is also changed. At this time, the changed pressure of each of the A port 310 and the B port 320 is transmitted through the pressure feedback channel 350 . When the pressure at both ends of the spool 250 is changed, the position in the longitudinal direction of the spool 250 is adjusted by the difference in the feedback force acting on the pressure feedback ports 252 on both sides. Therefore, since feedback by external pressure change can be structurally made, it is possible to perform precise control.

Hereinafter, an embodiment in which the position of the spool 250 can be precisely adjusted according to the present invention will be described with reference to FIGS. 8 and 9 . In this embodiment as well, it may be configured to include the same components as in the above-described embodiment,

8 is a perspective view showing the jig 230 and the hydraulic manifold 210 of another embodiment according to the present invention.

Referring to FIG. 8 , the jig 230 may include adjusting screws 241 , 242 , 244 capable of adjusting the position of the hydraulic housing block 220 inserted into the hydraulic housing block receiving groove 231 . . The jig 230 may be formed with an adjustment screw insertion hole extending from the outer surface to the hydraulic housing block accommodating groove 231 . The adjustment screw insertion hole may be configured to be inserted from both sides of the z-direction and the y-direction to a size in which the adjustment screw can be inserted from the outer surface of the jig 230 in FIG. 7 . The adjusting screws 241 , 242 , and 244 may be configured to support the exposed side of the hydraulic housing block 220 and to adjust a position thereof. As described above, the pressure feedback port accommodating groove 221 is provided in the hydraulic housing block 220 , and the pressure feedback port 252 of the spool 250 is inserted and assembled into the pressure feedback port accommodating groove 221 . Therefore, if the position of the hydraulic housing block 220 is adjusted, the position of the spool 250 can be adjusted.

9 is a state diagram of a jig for aligning the axis between the spool and the manifolds at both ends. Since the jig 230 is fixedly installed with the lower manifold 212 and the central manifold 211 , the hydraulic housing block 220 can move on the jig 230 when the adjusting screw is operated. That is, the position can be adjusted in two directions perpendicular to the longitudinal direction with respect to the spool 250 fixed on both sides to the hydraulic housing block 220 . That is, the position of the jig 230 can be adjusted to align the center of the axis between the spool 250 and the hydraulic housing block 220 .

On the other hand, the hydraulic housing block accommodating groove 231 may have a size somewhat larger than that of the hydraulic housing block 220 so that it can move in the y-axis and z-axis when the hydraulic housing block 220 is inserted. .

Referring to FIG. 9A , the concept of adjusting the relative positions of the jig 230 and the hydraulic housing block 220 in the y-axis direction by manipulating the second y-axis adjusting screw 244 is illustrated. The hydraulic housing block 220 may be pushed to the left in FIG. 9A by manipulating the second y-axis adjusting screw 244 . In this case, one side of the spool 250 is moved in the y+ direction. Meanwhile, although not shown, the hydraulic housing block 220 can be moved in the y- direction by operating the first y-axis adjusting screw 241 on the contrary.

Referring to FIG. 9B , the concept of manipulating the hydraulic housing block 220 in the z-direction is illustrated. By manipulating the z-axis adjusting screw 242, the hydraulic housing block 220 can be moved in the z-direction. Finally, by adjusting the position of the hydraulic housing block 220, the position of the spool 250 in the central manifold 211 can be finally adjusted, so that concentric alignment can be precisely performed.

As described above, in the pressure feedback servo valve according to the present invention, since the pressure feedback channel connected to the rod side can transmit the feedback force to the spool, direct force and torque control without a separate sensor is possible only with an electric signal. In addition, it is backdrivable, and it is possible to safely interact with the external environment and control it.

In addition, it is possible to alleviate the problem of interference caused by frictional force and concentricity of the spool, thereby improving the hysteresis problem of the existing servo valve and performing more precise control.

100: torque motor 110: armature
120: flapper 130: feedback spring
200: body part
210: hydraulic manifold 211: central manifold
212: lower manifold 213: side manifold
220: hydraulic housing block
221: pressure feedback port receiving groove
230: jig
231: hydraulic housing block receiving groove
232: adjustment screw insertion hole
241: first y-axis adjustment screw 242: z-axis adjustment screw
244: second y-axis adjustment screw
250: spool 251: extension
252: pressure feedback port 253: groove
254: spool chamber 260: sleeve
270: nozzle
310: A port 320: B port
330: tank port 340: pressure port
350: pressure feedback channel
1000: actuator 1110: fixed part vane
1200: rotator 1210: rotator vane
1300: pressure chamber

Claims (12)

a torque motor configured to operate a flapper that selectively opens and closes the pressure nozzle according to an external signal;
a body portion having one side connected to the torque motor and comprising a sleeve communicating with the A port, the B port, the tank port, and the pressure port;
a spool configured to be reciprocable in a predetermined section within the sleeve and configured to determine a flow path of the fluid according to a position; and
and a pair of pressure feedback channels configured to transmit pressure from the A port and the B port to both ends of the spool, respectively. According to claim 1,
The spool is
The pressure feedback servo valve, characterized in that it is configured to move in the longitudinal direction according to the pressure difference applied to the both ends when the pressure is changed in the A port or the B port. 3. The method of claim 2,
The spool is
The pressure feedback servo valve further comprising a pair of pressure feedback ports extending in the longitudinal direction so that both ends can be respectively inserted into the pair of pressure feedback channels. 4. The method of claim 3,
The pressure feedback servo valve, characterized in that the cross-sectional area of the pressure feedback port is configured to be smaller than the inner diameter of the sleeve. 5. The method of claim 4,
The pair of pressure feedback ports,
and are configured to maintain respective inserted states in the pair of pressure feedback channels within a longitudinal stroke of the spool. 4. The method of claim 3,
and the pressure feedback port includes at least one groove cut along a rotation radius to reduce friction when moving in the longitudinal direction within the pressure feedback channel. 4. The method of claim 3,
The pressure feedback channel is a pressure feedback servo valve, characterized in that formed in the body portion. 4. The method of claim 3,
The body part,
The torque motor is connected to the upper side,
a hydraulic manifold configured so that the sleeve and the spool can be disposed therein, and having a plurality of flow paths to be connected to the A port, the B port, the tank port, and the pressure port;
a pair of hydraulic housing blocks configured to be inserted into both ends of the spool exposed on both sides of the hydraulic manifold; and
and a jig configured to move the pair of hydraulic housing blocks relative to the hydraulic manifold. 9. The method of claim 8,
The jig is
fixed to the hydraulic manifold at a plurality of points,
A hydraulic housing block accommodating groove configured to accommodate the hydraulic housing block is provided inside;
A pressure feedback servo valve, characterized in that at a plurality of points, an adjustment screw insertion hole that is formed through the hydraulic housing block receiving groove is formed. 10. The method of claim 9,
The adjusting screw insertion hole,
It is formed in two directions perpendicular to the longitudinal direction of the spool,
A pressure feedback servo valve, characterized in that it is configured to move the position of the hydraulic housing block as the adjusting screw is inserted. 4. The method of claim 3,
One end is connected to the flapper,
The other end is supported on the central portion in the longitudinal direction of the spool,
The pressure feedback servo valve according to claim 1, further comprising a feedback spring that provides a restoring force so that the spool returns to the neutral position. 11. The method of claim 10,
At least a portion of the hydraulic feedback channel is formed in the hydraulic housing block,
The pressure feedback port of the spool is configured to be inserted at least partially into the hydraulic feedback channel formed in the hydraulic housing block.

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